1. Field of the Invention
The present invention relates generally to batteries and, more particularly, to preventing reverse polarity contact between terminals of a standard dry cell battery and device contacts in a battery compartment in which the battery is installed.
2. Related Art
Electrical devices commonly derive their power by way of one or more batteries that are housed within a compartment associated with the device. The battery compartment typically is integral with the electrical device. Alternatively, the battery compartment can be provided remotely from the electrical device with a connection thereto via conductor elements such as electrical wires.
There are numerous types of primary (non-rechargeable) and secondary (rechargeable) dry cell batteries. Dry cell batteries are commercially available in a number of well-known sizes and configurations such as the standardized AAA, AA, C, and D battery sizes. The corresponding battery compartments have electrical contacts for contacting the terminals of the dry cell batteries installed within the compartment. These contacts are commonly referred to as either battery contacts (functional perspective) or device contacts (location perspective), latter term being used herein. When one or more dry cell batteries are installed in such battery compartments, the device serves as an electrical load placed across the terminals of the installed battery/ies, consuming battery power in the form of a current drawn from the battery/ies.
Dry cell battery compartments have at least one battery cradle with positive and negative contacts disposed on opposing ends thereof. The negative contact, commonly in the form of a planar tab or a conical coiled spring, abuts or contacts the negative terminal of the installed dry cell battery. The positive contact, commonly in the form of a planar tab, contacts the positive terminal of an installed dry cell battery. In compartments that house more than one dry cell battery, the batteries will be physically arranged either in series or parallel. In a series arrangement, the batteries are positioned in a single battery cradle with the planar surface of the positive terminal button abutting the planar negative terminal surface of a forward adjacent battery. In such embodiments, the positive terminal of the forward-most battery abuts the positive device contact while the negative terminal of the rear-most battery abuts the negative device contact. In a parallel arrangement, a pair of positive and negative device contacts is provided in each battery cradle of the compartment to electrically contact a dry cell battery installed therein.
To deliver power to the device, the dry cell batteries must be installed with a proper polarity connection to the device. That is, the negative device contact must physically contact the negative terminal of the installed battery while the positive device contact physically contacts the positive battery terminal. A well-documented problem with standard dry-cell batteries is that they can be inadvertently installed in the battery compartment with the polarity reversed; that is, with the positive battery terminal abutting the negative device contact and the negative battery terminal abutting the positive device contact. This reverse polarity arrangement results in the application of a reverse voltage to the device which can damage or degrade device components.
Traditional approaches to solving this problem primarily include the use of an electronic protection circuit that controls the power provided to the device by the installed dry cell battery/ies. There are a number of drawbacks to such conventional approaches. For example, the electronic protection components can consume considerable battery power thereby increasing the total power drawn from the installed dry cell battery/ies. Such increased power consumption can decrease the terminal voltage of the installed battery/ies to below a voltage required to operate the device. To increase the battery terminal voltage to that required by the device requires the implementation of additional or larger batteries. In addition, an increase in power consumption accelerates the rate at which rechargeable batteries are depleted. Other drawbacks include the cost, reliability, maintenance, warranty costs, etc., that are associated with the use of active, that is, power consuming, electronic components.
In one aspect of the invention, a reverse polarity exclusion device is disclosed. The device is constructed and arranged to prevent reverse polarity contact between a positive device contact disposed in a battery compartment cradle and a negative terminal of a standard dry cell battery installed in the cradle.
In another aspect of the invention, a battery compartment is disclosed. The battery compartment operationally houses at least one dry cell battery having a cylindrical casing with positive and negative terminal surfaces on opposing ends thereof. The positive terminal surface has a button protruding from the casing. In this aspect of the invention, the battery compartment is configured with positive and negative device contacts disposed in opposing ends of each battery cradle of the battery compartment to contact positive and negative terminals, respectively, of a dry cell battery installed therein. The battery compartment also comprises a reverse polarity exclusion device disposed in each battery cradle. The device is interposed between the positive device contact and a dry cell battery installed in the battery cradle. The device permits the positive terminal button to abut the positive device contact while preventing the negative terminal of the installed battery from abutting the positive device contact.
In a still further aspect of the invention, an insulating spacer for use in each battery cradle of a battery compartment is disclosed. The battery compartment is configured to operationally receive a battery that comprises first and second opposing polarity terminals disposed on opposing ends thereof, with the first terminal having a raised surface with a predetermined configuration. The insulating spacer is constructed and arranged to prevent reverse polarity contact between the second polarity terminal and a first polarity device contact disposed in each battery cradle, and to allow the raised surface of the first terminal to contact the first polarity device contact.